How to stop Reality Warping? With Better Reality Warping! That's the obvious answer. Having some kind of immutable reality that they can't change is the more interesting answer.
Of course neither of those work for this scenario, and the MunchKING would like to wait until they are actively malevolent towards somebody rather than just a prankster before he breaks out the sneaky teleport-murder to stop them...
The dangerous play is to volunteer to play their little game so no one else is affected by them.